The present invention relates to a valve for adding air to the intake line of an internal combustion engine, particularly Otto-cycle engines, during the deceleration phase with a diaphragm which is controlled by intake pipe pressure, acts against the force of a spring and is located in a can or metering member dividing it into two chambers. The diaphragm actuates a valve via a rod, and the chambers are connected via a calibration and a check valve.
The purpose of such an arrangement is the reduction, during deceleration, of the fuel deposited on the intake pipe walls and the prevention of peak values in the emission of CH and CO by making the mixture leaner by means of the added air.
The disadvantages of this known valve is that in deceleration there is only a brief addition of air which effects the required "leaning" of the mixture that is sufficient for normal driving operation. With longer deceleration phases, after the valve is closed, which takes place after the pressure is equalized via the calibration located between the chambers, there is an increase of the emission values by evaporating of more fuel deposited on the intake pipe walls. With maintained deceleration and by lowering the intake pipe pressure when the extra-air valve is closed again, at higher rpm's the underpressure limit can be exceeded; as a result, the incombustible mixture passes through the cylinders into the exhaust system and there leads, at an afterburner, to thermal damage through overheating.
It is, therefore, an object of the present invention to provide a valve for the addition of extra air for longer deceleration phases, such as downhill runs, where the appearance of emission peak values by evaporation of fuel deposited on the intake pipe walls is avoided, and a sufficient amount of air is available for a proper combustion in the cylinder.
Another object of the present invention is to provide an arrangement which is simple in construction and may be economically fabricated.
A further object of the present invention is to provide an arrangement, of the foregoing character, which has a substantially long operating life and may be readily and economically maintained in service.